WhatWeb identifies websites. It's goal is to answer the question, "What
is that Website?". WhatWeb recognises web technologies including content
management systems (CMS), blogging platforms, statistic/analytics
packages, JavaScript libraries, web servers, and embedded devices.
WhatWeb has over 900 plugins, each to recognise something different.
WhatWeb also identifies version numbers, email addresses, account ID's,
web framework modules, SQL errors, and more.

WhatWeb can be stealthy and fast, or thorough but slow. WhatWeb supports
an aggression level to control the trade off between speed and
reliability. When you visit a website in your browser, the transaction
includes many hints of what web technologies are powering that website.
Sometimes a single webpage visit contains enough information to identify
a website but when it does not, WhatWeb can interrogate the website
further. The default level of aggression, called 'passive', is the
fastest and requires only one HTTP request of a website. This is
suitable for scanning public websites. More aggressive modes were
developed for in penetration tests.
